Field of the Invention
The present invention relates to an image forming apparatus adopting an electro-photographic recording system or the like such as a copier, a facsimile machine, a laser beam printer, and a multi-function printer.
Description of the Related Art
An image forming apparatus adopting an electro-photographic recording system such as a copier, a facsimile machine, a laser beam printer, and a multi-function printer includes a transfer structure transferring a toner image formed on an image carrier such as a photosensitive drum and an intermediate transfer belt to a sheet-like recording medium (referred to simply as a ‘sheet’ hereinafter). A transfer structure disclosed in Japanese Patent No. 5198515 includes an image carrier and a transfer member such as a transfer roller being in contact with the image carrier and forming a transfer nip portion.
The transfer structure disclosed in Japanese Patent No. 5198515 includes a metal plate guiding the sheet to the transfer nip portion. A variable resistor (resistive element) is provided on a path of a grounding wire extending from the main guide portion.
If no variable resistor is interposed, it is unable to restrain the electric current from flowing from the transfer member to the metal plate through the sheet. Thus, much current from the transfer member flows to the metal plate, and an amount of current which should originally flow from the transfer member to the image carrier decreases, causing defective transfer of the toner. The provision of the variable resistor permits to restrain the current from flowing from the transfer member, transferring the toner image, to the metal plate and to prevent the defective transfer of the toner. However, a more low cost apparatus has been desired.